Antenna



April 7, 1942; w. PETERS ANTENNA Filed Sept. 30 1939 YINVENTOR WILHELMPETERS TRANSMITTER Patented Apr. 7, 1942 ANTENNA Wilhelm Peters, Berlin,Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphicin. b. H., Berlin, Germany, a corporation of Germany ApplicationSeptember 30, 1939, Serial No. 297,296 In Germany July 21, 1938' 9Claims.

The invention relates to an antenna arrangement, more especially forshort waves and ultrashort waves such as is used primarily for sendingout television programs. Therefore, the antenna must be matched with thetransmitter for a very wide frequency band. The maximum radiation shouldbe directed towards the horizon to cover as wide a territory aspossible. The radiation upwards should be but slight. Furthermore, theradiation about the antenna should be as uniform as possible, but therealso should be the possibility of providing a preferred radiation in theone or the other direction. Since a wide frequency band is to betransmitted, which means that the amplitudes of the various frequencieswithin the band are to be radiated in a uniform fashion, the wattlessresistance within the frequency range must be constant, at any rate itshould vary at least to a very slight degree only. Furthermore, theantenna should have a high radiation resistance and high degree ofefficiency of the radiation in order to realize" as high an intensity ofthe receiving field as possible.

Attempts have been made to fulfill these conditions by means of a coneshaped antenna or double cone antenna which is made to oscillate instanding waves and which is tuned to the carrier wave. For the choice ofthis antenna the important point was that the cone shape has a lowerwave resistance than a corresponding rodshaped antenna and that,therefore, for variation of the frequency in the vicinity of the tuningfrequency a lower gradient of the wattless resistance exists.Unfortunately, the radiation conditions of the cone antenna are in thecase of standing waves poorer than in the rod-shaped antenna since, dueto the difference in travel length of the waves, the useful fieldintensity radiated decreases in the horizontal while theradiationupwards increases in an oblique direction in an undesirable way.

The invention described in the following aims at providing an antennashape whose wattless resistance practically disappears and which stillassures a more favorable radiation than does the ordinary cone antenna.In order to obtain a matching of the transmitter with the antennathroughout a wide frequency band, the arrangement according to theinvention uses individual radiators which are made to oscillate intravelling waves. However, such radiators have, as is known, a highlyunilaterally directional diagram. Hence, with a single antenna excitedin progressing waves, a horizontal non-directional diagram can never beobtained. This is accomplished in accordance with the invention in thata suitable number of such radiators excited by travelling waves aredisposed symmetrically about a center, more especially such that acone-like, or other rotationally symmetrical combination of. radiatorsis employed. The lengths of said radiators lie along the surface of arotationally symmetrical conic solid of revolution and are preferablyconnected to the excitation source at their ends which are most closelyadjacent. The further advantage of utilizing travelling. waves residesalso in the fact that a unilateral directive ray action is therewithobtained. Therefore, a favorable shielding of the frontal radiators withrespect to those at the rear can be achieved and vice versa, so thatdisturbances caused by travel differences are prevented. In this way theradiation in the main direction of the ray, for instance in thehorizontal, will be amplified. In order to attain highest rayintensities there is an optimum angle of divergence of the cone.

Antennas with progressing waves are known as such in the form ofdirectional radiators, for instance as single wire-Beverage antenna, astwin wire V-antenna, or as four wire-rhombic antenna. These antennas arebuilt ordinarily to provide a horizontal polarization of the electricalfield strength so that the wires extend parallel to the ground. Since,in the above stated modes of construction, the antennas are built forwide frequency ranges extending from about 15 m. to m., the radiatorlength must be several wavelengths, in order to prevent the radiationfrom being influenced by the variation of the wavelength. Fornon-directional radiators which operate with a single carrier, forinstance antennas for television, relatively shorter radiation wires ofabout one-half wavelength and less can be employed advantageously. Inaccordance with the invention in order to realize a horizontalnon-directional radiation a number of elementary radiators of V-shape,for instance, are so arranged in a circle that the sides thereof form acone, as shown in'Figure 1, while Figure 2 shows an example ofconstruction for a rotary field antenna formed of four verticallydisposed rhombi 2l24 extending in four directions and fed in a phasesequence; Figure 3 shows the arrangement of the radiators on the surfaceof a conic solid of revolution with a ring-like connection and Figure 4shows an example of construction of a rotary field antenna with returnfeed to the radiator ends nearest the transmitter, and Figure 5 shows amodification of Figure 3. The return line, according to Figure 1, is soarranged in the axis of the cone that the return of two diametricallysituated radiators a and b are relatively displaced by such traveldifference that the radiators of the partial waves of the central wireseliminate one another. This can be accomplished, for instance, by meansof phase shifting loops 0 and d which for variation of the wavelengthmust be altered. This difiiculty can be overcome by rectifying thecurrent of the travelling waves before its return.

The assembling of individual radiators having travelling waves of equalphase furnishes a more or less star-shaped diagram depending on thenumber and diagram sharpness of theindividual radiators. In order toround off still more this diagram, the individual radiators are, inaccord ance with the present invention, fed in a phase sequence movingabout the center of the arrangement, such that a rotating field will beobtained as radiation field which rotates with the frequency of thecarrier wave, or fraction, or multiplethereof. 'In accordance with afurther idea of the' invention a non-directional radiation antennaarrangement is'formed by several directional individual radiators suchthat several directional antennas are excited by travelling waves havingsuch relative phases that a rotating radiationfield is produced. Theindividual radiators are arranged preferably on surfaces of revolutionsuch as cones, or double cones.

Aside from the already mentioned advantage, namely, that the wattlessresistance and the gradient of the wattless resistance are equal to zeroin a very wide frequency range and that the ray action is unilateral,such an antenna arrangement has the following further advantages: Thedifliculty of the return through a non-radiating wire is overcome sincethe sum of the currents must always be zero at the point of joining. Bymeans of the rotational field it is accomplished that two diametralradiators or generally two radiators relatively displaced by a poledivision are connected together through a terminal resistance R.However, the energy can be made available again for the transmitter bymeans of coupling the rotary field and by return, as shown in Figure 4.The coupling of the rotary field affords in particular a very simpleregulation for variation of the wavelength. Also, in this case there isobtained a most favorable opening angle and resultant diameter in whichthe conically arranged radiators are situated. More especially may it befavorable to arrange the antenna in a frustum of a cone. The connectingtogether of the individual radiators in the base surfaces of the conecan be done by means of radial wires or also by means of annular rings.

The coupling in each of the examples may be done by inductive means orcapacitive means. In all these examples of construction the antennas areformed by four elements. The radiators spacially displaced at 90 are fedwith voltages displaced by 90. The voltage is produced, for instance, ina'known manner by means of phasing loops, chain conductors or by twogenerators having their phases displaced by 90. The antenna inaccordance with the invention may, as is obvious, also consist of anyother even number of individual radiators such as six radiators forinstance. In this case the Voltages in the case of rotary field feed,must be displaced by 60.

Figure 2 represents an example of construction for the production ofvoltage oscillating in a displaced fashion-whereby a chain conductorarrangement K is used. If the wave resistance of the two diametricallydisposed radiator lead-ins is additionally matched with the respectiveradiation resistance, it can be accomplished that the ohmic terminalresistance R remains relatively low while the efficiency of the antennais favorableeven without the use of a special return feed. The decreaseof the wave resistance towards the end is obtained in this case in thatp the individual wires are substituted each by three wires for instance,as shown by radiator 5l54 of Figure 5, which diverge towards the end. InFigure 4, the non-radiated energy is applied again to the transmitterthrough a rotary field coupling with the aid of a rotation fieldtransformer T such as is proposed already for rhombus antennas accordingto a .copending Moser application, Serial #205,198, filed April 30,1938. By twisting the primary part of the transformer relative to thesecondary part thereof the energy feed can be accurately set forprogressing waves on the radiator wires.

The arrangements just described relate to nondirectional radiators forvertically polarized field intensities such as required in particularfor television purposes. However, cases are conceivable in whichnon-directional radiators may be employed for horizontally polarizedfield intensities such as, for instance, for electric markers or fordirection finding utilizing several radiators radiating rotating fieldsof opposite direction, of rotation. The idea of the invention of' therotary field antenna with progressing waves can also be applied and usedfor non-directional radiators for a horizontally polarized field.

I claim:

1. An antenna comprising a'plurality of conductors arranged with theirlength parallel to the eneratrix of the surface of a conic solid ofrevolution, means for so energizing said conductors at their mostclosely adjacent ends and means for so terminating said conductors attheir other ends that a travelingwave is set up along said conductors,said conductors being so energized from said means that theinstantaneous phase relationshipof energy in said conductorsprogressively advances around said surface whereby a rotating field ofradiation is established.

2.'An antenna comprising a plurality of conductors arranged-with theirlength parallel to the generatrix of the surface of a conic solid ofrevolution, means for energizing said conductors at their mostcloselyadjacent ends, the instantaneous phase relationship of the energyin adjacent conductors progressively advancing around said surfacewhereby a rotating field of radiation is established and means connectedto the'outer ends of said conductors for preventing the reflection ofenergy from said outer'ends back along said conductors whereby atraveling wave is set up along said conductors.

3. An antenna comprising a plurality of conductors arranged with theirlength parallel to the generatrix of a conical surface'of revolutionhaving the axis of revolution vertical, means for so energizing saidconductors at their most closely adjacent ends that the instantaneousphase relationship of the energy in adjacent conductors progressivelyadvances around said surface whereby a rotating field of radiation isestablished and means connected to the outer ends of said conductors forpreventing the reflection of energy from'said outer ends back along saidconductors whereby a traveling "wave is "set up 'along said conductors.

4. An antenna comprising a plurality of conductors arranged with theirlength parallel to the generatrix of a surface of revolution formed byrotating a rhombus about a vertical axis outside of said rhombus, meansfor so energizing said conductors at their inner ends that theinstantaneous phase relationship of the energy and adjacent conductorsprogressively advances around said surface whereby a rotating field ofradiation is established and means connected to the outer ends of saidconductors for preventing the reflection of energy from said outer endsback along said conductors whereby a traveling wave is set up along saidconductors.

5. An antenna comprising a plurality of conductors arranged with theirlength parallel to the generatrix of a surface of revolution formed byrotating a rhombus about a vertical axis outside of said rhombus, andmeans for so energizing said conductors at their inner ends and soterminating said conductors at their other ends that a, traveling waveis set up along said conductors, the instantaneous phase relationship ofthe energy in adjacent conductors progressively advancing around saidsurface whereby a rotating field of radiation is established.

6. An antenna comprising a plurality of conductors arranged with theirlength parallel to the generatrix of a conical surface of revolution,means for energizing said conductors at their more closely adjacent endsso that a traveling wave is set up along said conductors, theinstantaneous phase relationship of thelenergy in adjacent conductorsbeing such that a rotating field of radiation is established, and meansconnected to the outer ends of said conductors for preventing thereflection of energy from said outer ends back along said conductors,said last mentioned means comprising a series connected ring ofresistors joining said outer ends.

7. An antenna comprising a plurality of conductors arranged with theirlength parallel to the generatrix of the surface of a conic solid ofrevolution, means for energizing said conductors at their most closelyadjacent ends, the instantaneous phase relationship of the energy inadjacent conductors progressively advancing around said surface wherebya rotating field of radiation is established and means connected to theouter ends of said conductors for preventing the refiection of energyfrom said outer ends back along said conductors whereby a traveling waveis set up along said conductors, said last mentioned means comprising aseries connected ring of resistors joining said outer ends.

8. An antenna comprising a plurality of conductors arranged with theirlength parallel to the generatrix of the surface of a conic solid ofrevolution, means for energizing said conductors at their most closelyadjacent ends, the instantaneous phase relationship of the energy inadjacent conductors progressively advancing around said surface wherebya rotating field of radiation is established and means connected to theouter ends of said conductors for preventing the reflection of energyfrom said outer ends back along said conductors whereby a traveling waveis set up along said conductors, said last mentioned means comprisingmeans for conducting all radiation arriving at said outer ends to saidinner ends.

9. An antenna comprising a plurality of conductors arranged with theirlength parallel to the generatrix of the surface of a conic solid ofrevolution, means for so energizing said conductors at their mostclosely adjacent ends and means for so terminating said conductors attheir other ends that a traveling wave is set up along said conductors,said conductors being so energized from said energizing means that theinstantaneous phase relationship of the energy in said conductorsprogressively advances around said surface whereby a rotating field ofradiation is established, each of said conductors comprising a pluralityof wires connected together at said first mentioned ends and fanned outtowards the other ends.

WILHELM PETERS.

